The present invention relates to an improved DC motor control system.
In order to control or more particularly, to speed regulate the small-sized DC motors and especially those used in the audio equipment such as the record players, tape recorders and so on, a quartz resonator is generally used to generate the clock pulses which are compared with the pulses proportional to the rotational speed of a rotating body such as a turntable driven by a DC motor under control to detect the phase difference between them, whereby the rotation of the rotating body may be synchronized with the clock pulses.
In order to obtain the speed-above-normal signal, the starting signal, the brake-release signal and the normal or forward rotation signal used for displaying the normal or forward rotation in the DC motor control system of the type described above, use is made of a frequency generator for generating pulses whose frequency is proportional to the rotational speed of a rotating body driven by the DC motor and a frequency-voltage converter for converting the output pulses from the frequency generator into the DC signal the level of which is compared in an analog manner as disclosed in Japanese Laid-Open Patent application No. 52-1481. However, the motor control system or the motor speed regulation device of the type described cannot attain satisfactory results because of the production variation of parts characteristics and of the difficulty in attainment of compensation for temperature and voltage variations.